1. Field of the Invention
The present invention generally relates to cryogenic refrigerators, and more particularly to a cryogenic refrigerator including a compressor configured to feed a refrigerant gas.
2. Description of the Related Art
Cryogenic refrigerators such as Gifford-McMahon refrigerators (hereinafter referred to as “GM refrigerators”) and pulse tube refrigerators include a compressor configured to compress and increase the pressure of a low-pressure refrigerant gas collected from a cylinder or a regenerator (hereinafter referred to as “cylinder or the like”) and to re-feed the high-pressure (compressed) refrigerant gas to the cylinder or the like.
Further, a cryogenic refrigerator has been proposed that includes an intermediate buffer tank in order to reduce the size and the output of the compressor. (See Japanese National Publication of International Patent Application No. 2008-527308.) This cryogenic refrigerator is configured to feed a refrigerant gas stored in the intermediate buffer tank to the cylinder or the like before feeding a high-pressure refrigerant gas from the compressor to the cylinder or the like.